KR101628435B1 - Adhesive film, adhesive composition for the same and display member comprising the same - Google Patents

Abstract

The present invention relates to a pressure-sensitive adhesive film comprising a urethane functional group and having a ratio (B / A) of 180 占 peeling strength (B / A) of 5 or more after standing at 70 占 폚 for 180 minutes against 180 占 peeling strength , A pressure-sensitive adhesive composition therefor and a display member comprising the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pressure-sensitive adhesive film, a pressure-sensitive adhesive composition for the pressure-

The present invention relates to a pressure-sensitive adhesive film, a pressure-sensitive adhesive composition comprising the same, and a display member comprising the same. More specifically, the present invention relates to an adhesive film which improves reworkability by easily removing a film due to poor initial adhesion when a film itself is defective or bubbles are generated in a laminating process, and increases durability by increasing adhesive strength at high temperatures And a display member comprising the same.

Optical clear adhesive (OCA) films are used as interlayer adhesives for laminating components in an optical display device or in touch screen attachment of mobile phones as adhesive films. Particularly, a capacitive type touch pad among optical display devices is attached to a window or a film by an adhesive film to exhibit characteristics by detecting a change in capacitance of a window or a film. In the touchpad, the adhesive film is laminated between the window glass and the TSP sensor glass.

OCA film transmits light more than 97% and functions like glass, but it has better screen sharpness and better adhesive property than conventional double-sided tape. OCA film can be used not only for mobile phones but also for Tablet PCs and TVs whose display screens are medium and large size.

Rework may be required if foam or laminating defects occur during the laminating process of the OCA film. The adhesive film applied to the touch panel is usually discarded, and the bonded adhesive film can be separated by physical force at a high temperature using a wire.

In this regard, Korean Patent Publication No. 2011-0038058 discloses an adhesive sheet comprising a core layer and a first curable adhesive layer, wherein the core layer has a urethane acrylate unit.

An object of the present invention is to provide an adhesive film capable of improving the reworkability by easily removing a film because the initial adhesive force is low.

Another object of the present invention is to provide a pressure-sensitive adhesive film which can improve the durability by increasing the adhesive force at a high temperature.

It is still another object of the present invention to provide a pressure-sensitive adhesive composition for the pressure-sensitive adhesive film.

It is still another object of the present invention to provide a display member comprising the adhesive film.

The pressure-sensitive adhesive film, which is an aspect of the present invention, comprises a urethane functional group and has a ratio (B / A) of 180 占 peeling strength (B) after leaving at 70 占 폚 for 180 minutes against 180 占 peeling strength ) Can be 5 or more.

Another aspect of the present invention is a pressure-sensitive adhesive composition comprising (A) a (meth) acrylic copolymer and (B) a urethane (meth) acrylate polymer, wherein (B) B) may be contained in an amount of 1-9% by weight of the pressure-sensitive adhesive composition.

A display member that is another aspect of the present invention includes an optical film; And the adhesive film attached to one side or both sides of the optical film.

The present invention provides an adhesive film capable of improving reworkability by easily removing a film because the initial adhesive force is low. The present invention provides a pressure-sensitive adhesive film which can improve the durability by increasing the adhesive force at a high temperature.

1 is a sectional view of a display member according to one embodiment of the present invention.
2 is a cross-sectional view of a display member of another embodiment of the present invention.
3 and 4 are conceptual diagrams of shear stress specimens.

As used herein, "(meth) acrylate" may mean acrylate or methacrylate.

As used herein, "copolymer" may include oligomers, polymers or resins.

(B / A) of the 180 占 peel strength (B / B) after leaving at 70 占 폚 for 2 minutes against the 180 占 peel strength (A) at 25 占 폚 is 5 or more . If the ratio is less than 5, reworking may not be possible with respect to defects generated when the adhesive film is laminated on a substrate (e.g., a film, a glass, or a substrate), and a residue of the adhesive film may remain on the substrate even if it is reworked.

The ratio may preferably be 5-25.

The peel strength was measured at a rate of 0.3 m / min at a time point of 30 minutes after attaching an adhesive film (thickness: 175 mu m) laminated on a release film (for example, PET film) having a thickness of 50 mu m to a substrate (glass plate or ITO film) Is a value obtained by measuring the force at which the adhesive film is peeled off from the substrate at 180 DEG.

A is a value measured at 25 캜 after the adhesive film is attached to the substrate and aged at 25 캜 for 30 minutes.

B is a value measured at 25 캜 after the adhesive film is attached to the substrate and left at 70 캜 for 2 minutes and then aged at 25 캜 for 30 minutes.

A may be 300 g / inch or less, preferably 150-300 g / inch. In the above range, the initial adhesion is low, so that defects generated during the lapping process can be reworked.

B may be 1000 g / inch or more, preferably 1000-1500 g / inch. Within the above range, the adhesive strength is high in the final adhesive state, and reliability can be ensured.

The adhesive film has a shearing stress can be 15kgf / 4cm ² or more, preferably 15kgf / 4cm ² -40kgf / 4cm ² at 25 ℃. Within the above range, the pressure-sensitive adhesive film may have good endurance reliability.

The adhesive film may comprise a urethane functional group.

The urethane functional group may be derived from the urethane (meth) acrylate polymer contained in the composition for a pressure-sensitive adhesive film. The urethane functional group may be located in the main chain of the urethane (meth) acrylate polymer. The urethane (meth) acrylate polymer can lower the initial adhesive strength at room temperature of the pressure-sensitive adhesive film, thereby making it possible to rework the defects occurring in the laminating process.

The adhesive film can be used to adhere a glass, a substrate, or the like to an optical film as an adhesive layer adhered to one or both sides of the optical film.

The optical film may be a touch panel, a window, a polarizing plate, a color filter, a retardation film, an elliptically polarizing film, a reflective film, an antireflection film, a compensation film, a brightness enhancement film, It includes transparent electrode film of plastic LCD substrate, indium tin oxide (ITO), fluorinated tin oxide (FTO), aluminum doped zinc oxide (AZO), carbon nanotube (CNT), Ag nanowire or graphene can do.

Preferably, the adhesive film can be used as an optical clear adhesive (OCA) film or a touch panel film.

The adhesive film may comprise a cured product of a pressure-sensitive adhesive composition comprising a urethane (meth) acrylate polymer.

For example, the pressure-sensitive adhesive composition may be coated on a release film (e.g., a polyester or a polyethylene terephthalate film), followed by UV curing. UV curing can be performed at 30-200 mW / cm ² for 1 minute to 30 minutes. Preferably, oxygen can be cured in the blocked state.

The thickness of the coating is not particularly limited and may be 50 탆 to 2 mm, preferably 50 탆 to 1.5 mm.

The thickness of the adhesive film (thickness excluding the release film) is not particularly limited, but it may be 10 탆 to 2 mm, preferably 100 탆 to 1.5 mm.

Another aspect of the present invention is a pressure-sensitive adhesive composition comprising (A) a (meth) acrylic copolymer and (B) a urethane (meth) acrylate polymer.

( Meta ) Acrylic copolymer

(Meth) acrylic copolymer may be a copolymer of a monomer mixture comprising an alkyl (meth) acrylate having a C1-C20 alkyl group, an alicyclic group-containing (meth) acrylate and a hydroxyl group-containing monomer.

Preferably, the (meth) acrylic copolymer may be a non-heteroalicyclic copolymer containing no heteroalicyclic ring.

The monomer mixture may further include a monomer containing a carboxylic acid group, and a (meth) acrylate including a heteroalicyclic group.

The alkyl (meth) acrylate having a C1-C20 alkyl group may include a (meth) acrylic acid ester having a linear or branched alkyl group having from 1 to 20 carbon atoms. (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl Acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl And the like, but are not limited thereto. These may be used alone or in combination of two or more.

The alkyl (meth) acrylate having a C1-C20 alkyl group may be contained in an amount of 40 to 90% by weight of the monomer mixture or the (meth) acrylic copolymer. In the above-described range, bubbles and floating are not generated under heat and humidity conditions, and durability can be improved. Preferably 50 to 70% by weight.

Alicyclic (meth) acrylates are C3-C20 alicyclic (meth) acrylates. For example, isobornyl (meth) acrylate (IBOA), cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

The (al) alicyclic (meth) acrylate may be contained in an amount of 1-30% by weight of the monomer mixture or the (meth) acrylic copolymer. The heat resistance / durability in the above range can be increased, and the adhesion force can be increased. Preferably 15-25% by weight.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2- hydroxypropyl (Meth) acrylate, diethylene glycol mono (meth) acrylate, and the like, which are known in the art, such as polyoxyethylene (meth) acrylate, (Meth) acrylate having a C 1 -C 20 alkyl group having a hydroxyl group or a C 5 -C 20 cycloalkyl group; C1-C10 unsaturated alcohols including allyl alcohol, and the like, but are not limited thereto. These may be used alone or in combination of two or more.

The hydroxyl-containing monomer may be contained in an amount of 1-40% by weight of the monomer mixture or the (meth) acrylic copolymer. In the above range, there is an effect of increasing the adhesion force, and the durability is excellent, and no bubbles are generated under the moisture-resistant condition. Preferably 5-35% by weight.

The monomer containing a heteroalicyclic group may include a (meth) acrylic monomer having 4 to 6 carbon atoms and having a single ring alicyclic heterocycle having nitrogen, oxygen or sulfur. For example, acryloylmorpholine, and the like.

The monomer containing a heteroalicyclic group may be contained in the monomer mixture or the (meth) acrylic copolymer in an amount of 0-10% by weight. Within the above range, there may be an effect of improving durability, increasing adhesion, and preventing corrosion of the electrode film. Preferably 1 to 5% by weight.

The monomer containing a carboxylic acid group may be (meth) acrylic acid, itaconic acid, maleic acid, or fumaric acid. These may be used alone or in combination of two or more.

The carboxylic acid group-containing monomer may be contained in the monomer mixture or the (meth) acrylic copolymer in an amount of 0 to 10% by weight. In the above range, an increase in adhesion and an improvement in durability can be exhibited. Preferably 0.01 to 7% by weight, more preferably 0.01 to 5% by weight.

The (meth) acrylic copolymer can be produced by partial polymerization after the initiator is added to the monomer mixture. The polymerization is carried out until the (meth) acrylic copolymer has a viscosity at 25 ° C of 500-20,000 cPs. The coating is easy in the viscosity range and the workability is excellent. The polymerization can be carried out by polymerization by UV irradiation.

The initiator may preferably be a photopolymerization initiator. The photopolymerization initiator is activated by ultraviolet rays or electron beams to activate a carbon-carbon double bond in the adhesive film to generate a radical reaction.

Specific examples include, but are not limited to, alpha-hydroxy ketone type compounds, benzyl ketal type compounds, and mixtures thereof. Hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone, and the like. The initiators may be used alone or in combination of two or more.

The initiator may be included in an amount of 0.001 to 3 parts by weight, preferably 0.003 to 1 part by weight, based on 100 parts by weight of the monomer mixture for producing a (meth) acrylic copolymer. In this range, low light leakage and excellent endurance reliability can be obtained.

The (meth) acrylic copolymer may have a glass transition temperature (Tg) of -50 ° C to -5 ° C, preferably -30 ° C to -10 ° C. In the above range, the workability is excellent, and durability and adhesive strength are excellent.

The (meth) acrylic copolymer may have a viscosity at 25 ° C of 1,000 to 50,000 cPs, preferably 1,000 to 15,000 cPs, and more preferably 1,000 to 5,000 cPs.

The (meth) acrylic copolymer may have a weight average molecular weight of 1 to 4 million g / mol, preferably 1.5 to 3.5 million g / mol. Within the above-mentioned range, the pressure-sensitive adhesive composition can be cured to have durability even after being left in a high temperature and high humidity condition for a long time during production of the pressure-sensitive adhesive film, and the pressure-

(Meth) acrylic copolymer may be contained in an amount of 85 to 98% by weight, preferably 90 to 97% by weight, more preferably 91 to 97% by weight, and most preferably 94 to 97% by weight, based on the solid content of the pressure- have. Within the above range, effects such as high adhesion, film transparency, and durability can be obtained.

Urethane (meth) acrylate polymer

The urethane (meth) acrylate polymer may include a monofunctional (meth) acrylate polymer having a urethane group.

The urethane (meth) acrylate polymer may have a glass transition temperature of -5 ° C or higher. Within the above range, it is possible to impart reworkability by lowering the adhesive strength of the pressure-sensitive adhesive film at room temperature. Preferably, it may be -5 ° C to 5 ° C.

The urethane (meth) acrylate polymer may be contained in an amount of 1-9 parts by weight, preferably 2-9 parts by weight, more preferably 3-5 parts by weight, based on 100 parts by weight of the monomer mixture or the (meth) acrylic copolymer . Within this range, the increase in the adhesion at high temperature is good and the adhesion at room temperature is low.

The urethane (meth) acrylate polymer may be contained in an amount of less than 11% by weight, preferably 1-9% by weight, more preferably 2-9% by weight, and most preferably 2.5-5% by weight in the pressure-sensitive adhesive composition on a solid basis have. Within this range, durability may be good and the effect of restoring the film may be high.

The composition may further comprise at least one of an initiator and a crosslinking agent.

Initiator

The initiator may preferably be a photopolymerization initiator. Details of the initiator are as described above.

The initiator may be included in an amount of 0.001 to 5 parts by weight, preferably 0.003 to 1 part by weight, based on 100 parts by weight of the monomer mixture or the (meth) acrylic copolymer. Within this range, the curing reaction can proceed completely and the remaining amount of initiator remains to prevent the transmittance from deteriorating.

The initiator may be included in an amount of 0.001 to 5% by weight, preferably 0.001 to 1% by weight, based on the solid content of the pressure-sensitive adhesive composition. Within the above range, the remaining amount of the initiator remains to prevent the permeability of the adhesive film from decreasing.

Cross-linking agent

The crosslinking agent may preferably be a polyfunctional (meth) acrylate capable of curing with an active energy ray.

Examples of the polyfunctional (meth) acrylate include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol Di (meth) acrylate, neopentylglycol adipate di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, (Meth) acrylates such as ethylene oxide modified di (meth) acrylate, di (meth) acryloxy ethyl isocyanurate, allyl cyclohexyl di (meth) acrylate, tricyclodecane dimethanol Di (meth) acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylpropane (Meth) acrylate, adamantane (adamantane) di (meth) acrylate or 9,9-bis [4- (2-oxy-yl acrylate) phenyl] fluorene difunctional acrylate and the like; (Meth) acrylates such as trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri Trifunctional acrylates such as modified trimethylolpropane tri (meth) acrylate, trifunctional urethane (meth) acrylate or tris (meth) acryloxyethylisocyanurate; Tetrafunctional acrylates such as diglycerin tetra (meth) acrylate or pentaerythritol tetra (meth) acrylate; Pentafunctional acrylates such as dipentaerythritol penta (meth) acrylate; And dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate or urethane (meth) acrylate (e.g., an isocyanate monomer and trimethylolpropane tri Hexafunctional acrylates such as acrylonitrile-butadiene-acrylonitrile-butadiene-acrylonitrile, and the like, but are not limited thereto. They may be used alone or in combination of two or more.

Preferably, the cross-linking agent may be a polyfunctional (meth) acrylate of a polyhydric alcohol having 2 to 20 hydroxyl groups.

An isocyanate-based, epoxy-based, aziridine-based, melamine-based, amine-based, imide-based, carbodiimide-based, amide-based cross-linking agent or a combination thereof may be used.

The crosslinking agent may be contained in an amount of 0.01 to 5 parts by weight, preferably 0.03 to 3 parts by weight, more preferably 0.05 to 2 parts by weight based on 100 parts by weight of the monomer mixture or the (meth) acrylic copolymer.

The crosslinking agent may be contained in an amount of 0.01 to 5% by weight, preferably 0.03 to 3% by weight, based on the solid content of the pressure-sensitive adhesive composition. Within this range, there can be an effect of excellent durability and adhesion.

The pressure-sensitive adhesive composition may optionally contain a silane coupling agent (silane compound), a curing accelerator, an ionic liquid, a lithium salt, an inorganic filler, a softener, an antioxidant, an antioxidant, a stabilizer, A leveling agent, a defoaming agent, a plasticizer, a dye, a pigment (a coloring pigment, an extender pigment, etc.), a treating agent, a sunscreen agent, a fluorescent whitening agent (an antioxidant) , A dispersant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a lubricant and a solvent.

The silane coupling agent may further include an epoxy silane coupling agent, but is not limited thereto.

The additive (e.g., silane coupling agent) may be contained in an amount of 0.01-0.1 parts by weight, preferably 0.05-0.1 parts by weight, based on 100 parts by weight of the monomer mixture or the (meth) acrylic copolymer.

The additive (e.g., silane coupling agent) may be contained in an amount of 0.01 to 5% by weight, preferably 0.01 to 1.5% by weight, based on the solid content of the pressure-sensitive adhesive composition. Within this range, there can be an effect of excellent durability and adhesion.

The pressure-sensitive adhesive composition may have a viscosity at 25 ° C of 1,000 to 50,000 cPs.

The pressure-sensitive adhesive composition can be used for adhesion of an optical film including a polarizing film and a transparent electrode film.

A method for producing an adhesive film which is another aspect of the present invention comprises polymerizing a monomer mixture comprising at least one of an alkyl (meth) acrylate having a C1-C20 alkyl group, an alicyclic group-containing (meth) acrylate, (Meth) acrylic oligomer; Preparing a pressure sensitive adhesive composition by mixing the (meth) acrylic oligomer with a urethane (meth) acrylate polymer, an initiator, and a crosslinking agent; And UV-curing the pressure-sensitive adhesive composition.

The (meth) acrylic oligomer does not contain a solvent and may have a viscosity at 25 ° C of 1,000 to 50,000 cPs.

Another aspect of the present invention relates to a display member.

Wherein the display member comprises: an optical film; And the adhesive film attached to one side or both sides of the optical film.

1 is a sectional view of a display member according to one embodiment of the present invention.

As shown in Fig. 1, the display member includes an optical film 40; And an adhesive film (200) formed on the optical film (40).

The optical film may be a touch panel, a window, a polarizing plate, a color filter, a retardation film, an elliptically polarizing film, a reflective film, an antireflection film, a compensation film, a brightness enhancement film, Transparent electrode films such as plastic LCD substrates, indium tin oxide (ITO), fluorinated tin oxide (FTO), aluminum doped zinc oxide (AZO), carbon nanotubes (CNT), Ag nanowires and graphene . The method for producing the optical film can be easily manufactured by a person having ordinary skill in the art to which the present invention belongs.

For example, a touch panel can be formed by attaching a touch pad to a window or an optical film using the adhesive film. Or may be applied to an ordinary polarizing film as an adhesive film as in the prior art.

2 is a cross-sectional view of a display member according to one embodiment of the present invention. The display member may include a capacitive mobile phone.

2, a display device 1000 includes a liquid crystal panel in which polarizers 105 and 110 are laminated on both sides of an LCD cell 100 and a DAT (liquid crystal panel) in which a functional film (for example, antireflection film) a double sided adhesive tape 115, and a touch panel formed on the functional film. The touch panel unit includes a first adhesive film 125, a first transparent electrode film 145 laminated on the first adhesive film, a second adhesive film 130, and a second transparent electrode film 150. An overcoating layer 155 for electrodes and electrodes is formed on the second transparent electrode film, and a third adhesive film 135 and a window glass 140 are sequentially stacked on the overcoating layer. The air gap 160 may be removed when the adhesive film and the transparent electrode film are laminated together.

Hereinafter, the present invention will be described in more detail by way of examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Specific specifications of the components used in the following examples and comparative examples are as follows.

(A) (meth) acrylic copolymer: EHA (2-ethylhexyl acrylate), IBOA (isobornyl acrylate), HEA (2-hydroxyethyl acrylate)

(B) urethane (meth) acrylate polymer: (XSUO, Shinya T & C)

(C) Initiator: Irgacure 651 (2,2-dimethoxy-2-phenylacetophenone) (Shiba Japan K.K.)

(D) Crosslinking agent: HDDA (1,6-hexanediol diacrylate)

(E) Silane coupling agent: Siloxane-based epoxy silane (X-41-1059A, manufactured by Shinetsu)

Examples Comparative Example

(A) and 0.04 parts by weight of the component (C) described in Table 1 below (parts by weight) were mixed well in a glass container, the dissolved oxygen was replaced by nitrogen gas, and a low-pressure lamp was used for several minutes And partially polymerizing the mixture by irradiation with ultraviolet light to obtain a viscous liquid having a viscosity of about 1,500 cP. To the resulting composition were added 0.16 part by weight of the components (B), (D), (E) and (C) in the amounts shown in the following Table 1 and mixed well. The resultant mixture was applied onto a polyester film (release film) having a thickness of 50 mu m and subjected to mold release treatment to a thickness of 175 mu m. In order to remove oxygen adversely affecting the polymerization, the release film was covered and then irradiated from the two surfaces with a low-pressure lamp for about 3 minutes to obtain a transparent adhesive sheet.

The following properties of the pressure-sensitive adhesive films prepared above were evaluated and are shown in Table 1.

(1) Peel strength at 25 캜: Using a PET film (backing film) having a thickness of 50 탆, the produced pressure-sensitive adhesive film was laminated to the ITO film. After laminating, cut to a size of 25mm x 120mm and press with a roll weighing 2kg on STN Glass to complete the measurement specimen. Aging was carried out at 25 DEG C for 30 minutes and 180 DEG peel strength was measured at 25 DEG C at a rate of 0.3 m / min using a Texture Analyzer (TA.XT_Plus, manufacturer: Stable Micro System).

(2) Peel strength at 70 캜: A test piece is prepared in the same manner as described above. Leave for 2 minutes in convection oven set at 70 ° C. Aging was carried out at 25 DEG C for 30 minutes and 180 DEG peel strength was measured at 25 DEG C at a rate of 0.3 m / min using a Texture Analyzer (TA.XT_Plus, manufacturer: Stable Micro System).

(3) Peel strength ratio: The ratio of the peel strength at 70 DEG C to the peel strength at 25 DEG C measured above is calculated.

(4) Endurance reliability: A pressure-sensitive adhesive film is laminated on an ITO film, and a glass or polycarbonate film is laminated on the pressure-sensitive adhesive film to prepare a specimen. After autoclaving, the specimens are left for 500 hours at 60 ° C / 90% relative humidity. Peeling or peeling or bubble generation between the adhesive film as the adhesion surface and the glass or polycarbonate film is visually observed and evaluated according to the following criteria.

Good: Good (no bubbles or peeling)

?: Good (bubbles or peeling phenomenon somewhat)

X: poor (large amount of bubbles or peeling occurred)

(5) Shearing stress: The adhesive film and the ITO film were laminated as shown in Fig. 3 using a 2 kg roll. In Fig. 3, reference numeral 10 denotes an ITO film portion, and reference numeral 20 denotes a portion where an adhesive film and an ITO film are laminated. After removing the heavy film, STN glass is laminated as shown in FIG. 4 on the bottom of the portion where the adhesive film and the ITO film are joined using a laminating machine. In Fig. 4, reference numeral 10 denotes an ITO film portion, 20 denotes a portion where an adhesive film and an ITO film are joined together, and 30 denotes a STN glass. The specimens were aged at 70 ° C for 2 minutes in a convection oven at room temperature for 2 minutes, and shear stress was measured at a rate of 127 mm / min using UTM.

(6) Initial reworkability: An adhesive film is laminated on an ITO film, and a glass or polycarbonate film is laminated on the adhesive film to prepare a specimen. It is evaluated whether a residue of the adhesive film is formed on the adhered surface or an adherence failure of the glass or polycarbonate film occurs during the separation of the adhesive film. If there is no separation failure, no residue is found, and if there is a problem of separation failure or residue generation, it is evaluated as X.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Manufacturing method UV curing UV curing UV curing UV curing UV curing UV curing UV curing (A) EHA 65 65 65 65 65 65 65 IBOA 20 20 20 20 20 20 20 HEA 15 15 15 15 15 15 15 (B) content 3 3 5 - 5 5 10 Tg (占 폚) 5 -5 -5 - -50 -30 -5 (C) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 (D) 0.15 0.15 0.15 0.15 0.15 0.15 0.15 (E) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 25 DEG C Peel strength (a) (g / inch) 200 300 150 1500 1400 800 130 Peel strength at 70 DEG C (b) (g / inch) 1300 1500 1400 2300 2400 1500 520 Peel strength ratio (b / a) 6.5 5 9.3 1.53 1.7 1.875 4 Shear stress (kgf / 4 cm ² ) 15 or more 15 or more 15 or more 15 or more 15 or more 15 or more 8 or less Endurance reliability ○ ○ ○ ○ ○ ○ × Early reworkability ○ ○ ○ × × × ○

As shown in Table 1, the adhesive film of the present invention has a low peel strength at 25 DEG C, so that it can be reworked when defects are produced when the adhesive film is laminated, while the peel strength is high at high temperatures, Endurance reliability was good.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (20)

(Meth) acrylic copolymer and a urethane (meth) acrylate polymer, wherein the pressure-sensitive adhesive film comprises a cured product of a pressure-
The adhesive film was allowed to stand at 70 DEG C for 180 DEG peel strength (A) against ITO (indium tin oxide) film at 25 DEG C for 2 minutes, and then the ratio of the 180 DEG peel strength (B) to the ITO film (B / A) is 5 or more,
Wherein the urethane (meth) acrylate polymer is contained in an amount of 1-9 parts by weight based on 100 parts by weight of the (meth) acrylic copolymer.
Adhesive film.
The adhesive film according to claim 1, wherein the peel strength (A) is 300 g / inch or less and the peel strength (B) is 1000 g / inch or more.
The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive film has a shear stress of 15 kgf / 4 cm ² or more at 25 ° C.
delete The adhesive film according to claim 1, wherein the urethane (meth) acrylate polymer is contained in an amount of 2.5 to 5% by weight based on the solid content.
The adhesive film according to claim 1, wherein the urethane (meth) acrylate polymer has a glass transition temperature of -5 ° C or higher.
The composition according to claim 1, wherein the (meth) acrylic copolymer is a copolymer of an alkyl (meth) acrylate having a C1-C20 alkyl group, a (meth) acrylate containing an alicyclic group and a (meth) ≪ / RTI > copolymer.
The composition of claim 7, wherein the copolymer comprises 50-70% by weight of the alkyl (meth) acrylate having the C1-C20 alkyl group, 15-25% by weight of the alicyclic group containing methacrylate, (Meth) acrylate in an amount of 5 to 35% by weight.
The adhesive film of claim 1, wherein the composition further comprises at least one of an initiator, a crosslinking agent, and a silane coupling agent.
The composition of claim 9, wherein the composition is based on solids
100 parts by weight of the (meth) acrylic copolymer,
9 parts by weight of the above urethane (meth) acrylate polymer,
0.001-5 parts by weight of the initiator,
0.01 to 5 parts by weight of the crosslinking agent,
0.01 to 0.1 part by weight of the silane coupling agent
≪ / RTI >
The adhesive film according to claim 1, wherein the adhesive film has a thickness of 10 to 2 mm.
(A) 100 parts by weight of a (meth) acrylic copolymer,
(B) 1 to 9 parts by weight of a urethane (meth) acrylate polymer,
(C) 0.001-5 parts by weight of an initiator,
(D) 0.01 to 5 parts by weight of a crosslinking agent,
The urethane (meth) acrylate polymer (B) has a glass transition temperature of -5 캜 or higher,
The (meth) acrylic copolymer (A) is a copolymer of an alkyl (meth) acrylate (a1) having a C1-C20 alkyl group, an alicyclic (meth) acrylate (a2) ≪ RTI ID = 0.0 > a < / RTI >
The pressure-sensitive adhesive film formed from the pressure-sensitive adhesive composition was allowed to stand for 2 minutes at 70 ° C against the 180 ° peel strength (A) against an ITO (indium tin oxide) film at 25 ° C, Wherein the ratio (B / A) is 5 or more.
The pressure-sensitive adhesive composition according to claim 12, wherein the urethane (meth) acrylate polymer is a monofunctional urethane (meth) acrylate polymer.
delete The pressure-sensitive adhesive composition according to claim 12, wherein the (A) (meth) acrylic copolymer is a pressure-sensitive adhesive composition comprising 50-70% by weight of (a1), 15-25% by weight of (a2) Composition.
delete delete The pressure-sensitive adhesive composition according to claim 12, wherein the pressure-sensitive adhesive composition further comprises an epoxy silane coupling agent.
Optical film; And
The display element according to any one of claims 1 to 3 and 5 to 11, which is attached to one or both surfaces of the optical film.
The optical film according to claim 19, wherein the optical film is at least one selected from the group consisting of a touch panel, a window, a polarizing plate, a color filter, a retardation film, an elliptically polarizing film, a reflective film, an antireflection film, a compensation film, a brightness enhancement film, Film, surface protection film, plastic LCD substrate, indium tin oxide (ITO), fluorinated tin oxide (FTO), aluminum doped zinc oxide (AZO), carbon nanotube film, Ag nanowire- A display element comprising a graphene.

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